56 BRITISH FUNGI 



into the flower, and produces the black powdery mass of spores 

 known to farmers as " smut," which takes the place of a grain of 

 oats which under normal conditions would have been present. 

 The spores or " smut " when ripe are washed by rain or blown 

 by wind on to the ground, where they remain, and in due course 

 infect a succeeding crop of oats. Now, in this instance the fungus 

 practically lives actively as long as its host-plant does, and only 

 produces spores to tide it over that period of time when its host- 

 plant, being an annual, is not present. The points to notice in 



^^spsr^w 



Leaves of plum tree destroyed hy a fungus called 

 Hormodendron kordci. 



connection with this parasite are as follows : It causes no injury to 

 the host-plant during the period of vegetative growth of the latter, 

 but when the oat plant commences to form its seed, the fungus 

 steps in and prevents this operation by usurping the position 

 that the oat grain would have occupied under normal conditions, 

 thus an oat plant that is infected is prevented from reproducing 

 its kind by means of seed. To this extent the oat plant suffers, 

 due to the presence of the parasite. The parasite, on the other 

 hand, has not advanced beyond the stage of having to produce 

 spores for the purpose of perpetuating its kind from year to year. 

 The question. Why not ? will probabl}- suggest itself. Is it not the 



